void main() {
  Person obj = Person('狸花', 14);
  print(obj.name);
  Son obj1 = Son('Leven', '男', '游戏');
  print(obj1.name);
}

class Person {
  String name = '';
  int age = 0;
  Person(String name, int age) {
    this.name = name;
    this.age = age;
  }
}
class Son extends Person {
  String sex = '';
  String hobbit = '';
  Son(String name, String sex, String hobbit) : super(name, 0) {
    this.sex = sex;
    this.hobbit = hobbit;
  }
}